Windows Network Protocol Configuration on the Main /
File Server Computer
By default, newer installations of Windows default to a network protocol SMB2 and SMB3 that is faster than SMB1 but which usually causes damage to shared data files. I.e. it will often damage Shopkeeper data even though it is fine for Microsoft Office documents and web browsing.
All computers need to be configured with SMB1 turned on and SMB2 and SMB3 and OpLocks turned off.
While all computers have to be configured correctly, the most important first step is to configure the Main / Server computer correctly and then proceed to configure the workstations (the other "client" computers.)
The instructions directly from Microsoft (including the Registry approach) are on this support page:
http://support.microsoft.com/kb/2696547
If the Main / Server computer is running Windows 8 or 10 or later or Windows Server 2012 or later, press the Windows key or click the Windows button, then type POWERSHELL, find Powershell in the list, and right click it to get a blank command screen in which type or paste these lines with <Enter> after each:
Set-SmbServerConfiguration -EnableSMB2Protocol $false
Set-SmbServerConfiguration -EnableSMB1Protocol $true
Set-SmbServerConfiguration -EnableOplocks $false
For other versions of Windows, type these four commands:
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters" SMB1 -Type DWORD -Value 1 -Force
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters" SMB2 -Type DWORD -Value 0 -Force
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters" EnableOplocks -Type DWORD -Value 0 -Force
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\MRXSmb\Parameters" OplocksDisabled -Type DWORD -Value 1 -Force
or, in graphic form in case the text lines are wrapped as you view them:
Then restart the computer.
Note that if the server is configured with only SMB1 turned on, then any workstation with only SMB2 or SMB3 turned on would not be able to connect to the main/server computer.
For the Workstation / Client computers, see separate instructions to set or correct the network configuration.
This is unrelated to the SMB configuration, but it's often helpful to activate the Guest account on a Windows 10 computer acting as a file server, and that can be done by typing this command at an elevated CMD prompt:
net user guest /active:yes